1. Field of the Invention
This invention relates to an internal frame of a wheeled suitcase, and more particularly, to an internal frame comprising a base, a U-shaped frame mounted on top of the base, and a modular central frame mounted between the U-shaped frame and the base for strengthening the structure of the wheeled suitcase.
2. Description of the Prior Art
Wheeled suitcase are popular for traveling because they can easily be pulled rather than carried. In order to reduce tile overall weight of a suitcases, most wheeled suitcases use a light-weight internal frame with a layer of flexible material covered on its outside. In such design the internal frame becomes the most important component in supporting the structure of a wheeled suitcase.
My U.S. Pat. application Ser. No. 08/371,401, entitled AN INTERNAL FRAME FOR A WHEELED SUITCASE, filed Jan. 11, 1995, is herein incorporated by reference. The patent application describes an internal frame for supporting a wheeled suitcase comprising a base, a U-shaped frame mounted on top of the base, and a central frame installed between the base and the U-shaped frame for strengthening the structure of the internal frame. The central frame comprises a horizontal U-shaped member on its top end for supporting the top panel of the U-shaped frame. The front end of the U-shaped member can be used to support an external suitcase hanging over the front upper end of the wheeled suitcase. And the rear end of the central frame comprises a rod receiving means for receiving a slidable pull handle installed on the rear upper end of the wheeled suitcase for pulling or pushing the wheeled suitcase when it is tilted rearward.